All heretofore known machine-tools for milling, boring, and drilling that incorporate a mobile standard and a horizontal broach, present a mobile standard resting on a sole plate which slides on a fixed base, itself connected to a solid concrete mass. The broach is mobile vertically along the standard and may move horizontally along a perpendicular to the plane of displacement of the standard. These machines enable workpieces of very large dimensions, which remain fixed during the work, to be machined.
Such machines present two major drawbacks connected with their design. In the first place, they present a rigidity which varies with the vertical position of the broach, which means that they do not make it possible to carry out, under good conditions, either machining of blanks or finishing work when the broach is in a high position, due to the vibrations resulting from the lack of rigidity in the case of blanks and due to the deformations which are amplified as soon as the ratio of the height of the broach to the width of the slide rails increases in the case of finishing work. Secondly, the dimensioning of the standard necessary for obtaining a minimum rigidity results in the mobile assembly becoming very heavy, which means that these machines are relatively slow in their displacements and in their accelerations.
It is an object of the present invention to overcome these drawbacks and to propose a machine-tool incorporating a mobile standard and a horizontal broach, which allows perfect machinings both of blanks and for finishing, and which is rapid and precise.